dmaengine: dw-edma: Add pcim_iomap_table return check

Currently, is missing a null check on a pcim_iomap_table() return value
and this can lead to a null pointer dereference if the desired BAR
wasn't mapped previously.
Fix this by adding a null check and returning -ENOMEM.

Addresses-Coverity: ("Dereference null return")
Signed-off-by: Gustavo Pimentel <[e-mail]>
Link: https://lore.kernel.org/r/bc5e6b86[e-mail]
Signed-off-by: Vinod Koul <[e-mail]>

drivers/dma/dw-edma/dw-edma-pcie.c

···
 	dw->rd_ch_cnt = vsec_data.rd_ch_cnt;
 
 	dw->rg_region.vaddr = pcim_iomap_table(pdev)[vsec_data.rg.bar];
+	if (!dw->rg_region.vaddr)
+		return -ENOMEM;
+
 	dw->rg_region.vaddr += vsec_data.rg.off;
 	dw->rg_region.paddr = pdev->resource[vsec_data.rg.bar].start;
 	dw->rg_region.paddr += vsec_data.rg.off;
···
 		struct dw_edma_block *dt_block = &vsec_data.dt_wr[i];
 
 		ll_region->vaddr = pcim_iomap_table(pdev)[ll_block->bar];
+		if (!ll_region->vaddr)
+			return -ENOMEM;
+
 		ll_region->vaddr += ll_block->off;
 		ll_region->paddr = pdev->resource[ll_block->bar].start;
 		ll_region->paddr += ll_block->off;
 		ll_region->sz = ll_block->sz;
 
 		dt_region->vaddr = pcim_iomap_table(pdev)[dt_block->bar];
+		if (!dt_region->vaddr)
+			return -ENOMEM;
+
 		dt_region->vaddr += dt_block->off;
 		dt_region->paddr = pdev->resource[dt_block->bar].start;
 		dt_region->paddr += dt_block->off;
···
 		struct dw_edma_block *dt_block = &vsec_data.dt_rd[i];
 
 		ll_region->vaddr = pcim_iomap_table(pdev)[ll_block->bar];
+		if (!ll_region->vaddr)
+			return -ENOMEM;
+
 		ll_region->vaddr += ll_block->off;
 		ll_region->paddr = pdev->resource[ll_block->bar].start;
 		ll_region->paddr += ll_block->off;
 		ll_region->sz = ll_block->sz;
 
 		dt_region->vaddr = pcim_iomap_table(pdev)[dt_block->bar];
+		if (!dt_region->vaddr)
+			return -ENOMEM;
+
 		dt_region->vaddr += dt_block->off;
 		dt_region->paddr = pdev->resource[dt_block->bar].start;
 		dt_region->paddr += dt_block->off;